The invention relates in general to respirators and in particular to a new and useful device for the enrichment of respiratory air with oxygen, wherein the supply gas to be enriched can be supplied to at least one concentrator and from there to a product gas line in an adjustable concentration of enrichment.
For the enrichment of the supply gas, known devices use pressure exchange adsorption beds which are filled with zeolite. However, permeators equipped with an oxygen-permeable membrane can be used also. In the following, these two enrichment units will be referred to as concentrators. They are used in particular to ensure that the oxygen concentration required for the respiratory air supply of flight personnel used at various altitudes. Such a device is known from DE-OS 28 37 281.
In the known device the respiratory air to be enriched with oxygen is led through the concentrator, in which the nitrogen is retained, and the enriched respiratory air is supplied to the user. The concentration of the oxygen permeated depends essentially on the amount of supply gas flowing through it. If the user requires a lower oxygen concentration, the throughput of the concentrator is increased, the excess amount of enriched product gas being collected in a buffer container. If the amount taken from the buffer container falls below the amount delivered by the concentrator, the excess air is released into the surroundings.
As in the known device the concentration of the enrichment of the product gas is determined by the throughput of supply gas through the concentrator, an adjustment of enrichment to the product gas required usually results in an unnecessary loss of product gas.
If during an unexpected decompression in the personnel section the concentration of enrichment, particularly with an oxygen enrichment, has to be increased to the physiologically required parameters. With the known concentrator this can only be effected by reducing the throughput. In this case however, the increase of the oxygen concentration takes place at so large a time constant that a speedy change of the concentration of enrichment can not be realized. Therefore, an additional back-up system is required for the known device, which can deliver respiratory air with an increased oxygen concentration for a short period and at short notice.